I'd like to have users be able to click on a subject heading and see all of our holdings that employ that term, much like a library catalog record does. Perhaps this function is something that needs to be added to my stylesheet?

So that we can investigate more fully, would you mind clarifying your question some more? What do you mean by having "subject headings show up as links opnce rendered by the stylesheet"? Are you expecting terms to be linked to other parts of the finding aid? Something else?